Carburetor



Sept. 10, 1940. R, FISH 2,214,273

GARBURETOR Filed Feb. 10, 1934 5 Sheets-Sheet 1 TTORNEYS Sept. 10, 1940.R. sH

. cmaunnwon Filed Feb. 10, 19:54 is Sheets-Sheet 5 izz 'azai INVENTORJ5mv Roan "58H ATTORNEYS Patented Sept. 10, 1940 UNITED STATES PATENToer-ice 13 Claims.

This invention relates to carburetors for internal combustion motors.One object of the invention is to provide a carburetor in which thevarying mixture requirements under different motor operating conditionswill be met automatically and wthout the use of mechanically operated orspring operated fuel or air jets. Another object is to provideanimproved idling and starting system for carburetors. Another object isto provide improved control for the action of the carburetor duringrapid acceleration of the motor. A specific object is to improve uponthe carburetor disclosed in my prior application for patent Serial No.682,980, filed July 31, 1933, particularly in the direction ofsimplifying the mechanism thereof, decreasing its cost in manufacture,pro ducing greater compactness and improving the mixing of the fuel andair in correct proportions over the entire range of motor operatingcondi- 20 tions.

Referring to the drawings:

Fig. 1 is a top plan view of a down draft car" buretor embodying myinvention;

Fig. 2 is aside elevation thereof;

Fig. 3 is a section taken on line 3-3 of Fig. 1;

Fig. 4 is a section on line 4-4 of Fig. 1; Fig. 5 is a section on line55 of Fig. 4 with certain portions broken away; v

Fig. 6 is an enlarged sectional detail of the idling mechanism; r

Fig. '7 is a sectional detail on line 'l-'I of Fig. 5; Figs. 8 and 9 arerespectively a top plan and an end elevation of the throttle; Fig. 10 isa detail showing the manner the throttle is assembled on its shaft;

Fig. '11 is a perspective detail showing the assembly or the throttle,throttle shaft, and fuel arm:

Fig. 12 is a perspective view of the throttle;

Fig. 13 is a detail similar to Fig. 6 but showing theparts in positionfor starting with a cold motor;

Figs. 14 to 17 are diagrammatic views showing different positions of thethrottle;

Fig. 18 is a detail, corresponding to a portion of Fig. 3, showing amodified form of idling system;.

Fig. 19 is a similar view showing a second modifled form of idiingsystem;

Fig. 20 is a perspee re view of a modified form of throttle;

Fig. 21 is an end elevation of the form of throttle shown in Fig. 20;

Fig. 22 is a top plan, and Fig. 23 a side elevation, of a modified formof fuel arm; and

Fig. 24 is a detail corresponding to a portion of Fig. 3 but showing afurther modification.

Fig. -25 is a diagrammatic view of the several parts of the carburetorshowing the connection and function.

in which The carburetor has a body portion l5 form with a cylindricalbore or mixing passage It. In the present case, as contrasted with thecarburetor shown in my prior application, this bore is made cylindricalso-that it can be easily machined; the necessary variations in the formof the passage being produced by the formation of the throttle. At itsupper end the passage is preferably widened into the usual bell mouth|'I having an external flange l8 upon which an air cleaner can bemounted. The carburetor is secured to the intake manifold by suitablebolts passing through holes in a bottom flange l9. To one side of themixing passage IS a fuel chamber is formed, this being closed by a plate2| recessed into the body 5. A cap casting 22 is held by screws 23against the plate 2|, a gasket 24 being used to prevent leakage.

The casting 22 is provided with a float chamber 25. Extendingtransversely of this chamber is a pivot pin 30 (Fig. 2) upon which ismounted an angle lever conveniently made of pressed metal and having apair of substantially horizontal arms 3| and a vertical arm 32.' Thearms 3| are secured to a float 33 preferably of cork in any suitablemanner, such as riveting. The arm 32 bears against a needle 34 having atapered end 35 adapted to fit against a seat 38 formed in a nipple 31.The point of the needle is preferably blunted to reduce the movement ofthe float'necessaryto produce the required gasoline flow. .The

sides of the needle 34 are slabbed off so as to permit the passage offuel between it and the hole in the nipple in which it slides. The levelof the liquid in the float chamber can be adjusted accurately by varyingthe thickness of the askets 38 against which the nipple seats, or bybending the arm 32. I

Communication between the float chamber and the fuel chamber 20 issecured by holes 4|! and 4| (Fig. 5) formed in the plate 2|. Within thefuel chamber 20 is a fuel arm 42 secured preferably by a press fit onone end of the throttle shaft 43 (Fig. 11). The exposed end of thethrottle sha t bears hand throttle and foot accelerator levers 44 and 45(Fig. 3) of any desired type. The top of the fuel arm is madecylindrical as at 46 and fits snugly into the curved upper end of thefuel chamber. This cylindrical top is provided with a groove 41extending a considerable distance around its circumference and with agroove 48 opening sideways onto the side of the fuel arm adjacent theplate 2|, the two grooves being connected by a passage -|4|l. The groove41 communicates at its bottom end with the fuel chamber and-remains incommunication, throughout the movement of the throttle arm, with a hole49 (Fig. 4) passing throughthe Wall of the carburetor body into theportion of the passage l6 above the throttle. In order to regulate theamount of air or fuel which will pass through the hole 49 a. jet 50 islocated in the hole. This jet is conveniently formed from acartridge-shaped piece of metal adapted to be held within the holemerely by being forced therein. Hole 49 is preferably reduced to form ashoulder against which the jet is driven. A small drilled hole in theend of the jet 50 gives the desired opening, this constructionpermitting the jet to be replaced by another with a different size holewhen desired. The groove 48 is less in extent than the groove 41 andcommunicates with the upper portion of the float chamber by means ofhole 5! in the plate 2|. The cross passage I furnishes a connectionbetween the groove 41 and the hole 5| and thus keeps the air pressuresin the float chamber and in the delivery side of the fuel chambersubstantially equal. It also serves as a. by-pass, together with hole5|, to give a control of the accelerating action of the fuel arm whichwill be described below. It may also be noted here that the pressure inthe passage 419 is slightly below that in the float chamber due to thelocation of the passage 49 in a more constricted part of the mixingpassage than the jet 13 which governs the float chamber pressure as willbe de-' scribed. The passage 50 will thus assist in keeping the pressureor delivery side of the fuel chamber 2!! always full of fuel. In fact,the reduction in pressure due to the passage 59 can readily be made solarge that without the balancing effect of the connection M0, 5| to thefloat chamber, fuel would actually be raised out of the passage 50.formed in the plate 2| on what may be termed the inactive side of thefuel chamber to prevent the trapping of air therein.

Before the fuel arm and the throttle shaft are assembled the throttleshaft is formed with an axial bore 54 (Figs. 4 and 10). Two long bores55 and 56 are formed in the fuel arm, extending from the cylindrical topof the arm down to a point closely adjacent its bottom. A hole 51 isformed from one side of the throttle shaft into its central bore and aparallel hole 58 is passed completely through the throttle shaft andprovided with screw threads. The shaft and the fuel arm are assembled sothat hole 51 faces the bottom side of the long bore 55, the top part ofthe throttle shaft serving to block off the upper portion of this boreso that no communication is afforded between the bottom end of the bore55 and the groove 41. A jet 59 is then threaded into the hole 58 fromabove, serving both to regulate the amount of air which, can passdownwardly into the bore 56 and to block off all directcommunicationbetween the bore 54 and the bore 56. This jet also acts asa plug closing oif the end of the bore 54 which lies adjacent the plate2| A series of holes 60 are passed through one wall of the arm andthrough the partition separating the bores 55 and 56, the portion ofthese holes in the outer wall of .thearm being then closed by plugs 6|.These holes permit the passage of fuel,

air, or both from' the bore 56 into the bore 55 in a manner which willbe described below. Thelower end of the bores 55 and 56 are opened tothe pressure side of the fuel arm by jets I30 and BI respectively. Thejet l3l provides a delicate adjustment of the flow of fuel through themain fuel jets, particularly effective at wide throttle openings, andmay be omitted if desired.

Fuel flows into the fuel chamber through the hole 60 in the pla t'e-2l.If the arm 42 is swung A hole I88 (Fig. 5) is preferably toward theright in Fig. 5 fuel would tend to be pushed back through this holeunless some provision were made for preventing it. A light springfeather valve 65,the free end of which moves between the hole 40 and astop plate 66, acts as a check valve to prevent this reverse movement ofthe fuel. The feather valve and the stop plate are conveniently held tothe plate 2| as by a screw 61. As in my prior application referred to, agroove 10 in the body l6 registers with a hole II in the fuel arm whenthe latter is near its open throttle position to facilitate flow of fuelinto the passage 55 and somewhat enrich the mixture, producing the ratioof fuel and air necessary to give the highest power. A hole 12 formed inthe carburetor body connects the upper portion of the float chamber 25with the main passage I6 as is best shown in Fig. 4, the amount of airpassing through this hole being regulated by an apertured jet '3 formedin the same manner as jet 50. The relative size of the jets has adecided effect on the performance of the carburetor as will .bedescribed. I

The bore 54 which extends into the throttle shaft 43 is provided withone or more radial holes 15 (Fig. 10) extending into one or moreexternal longitudinal grooves 16 in the throttle shaft. In the caseshown three of these holes 15 have been provided. The throttle whichfits upon the throttle shaft has the shape of a sphere with its sidesflattened off. The spherical surface is left around the central zone ofthe throttle so that it will substantially fill the passage l6 when thethrottle is closed as in Fig. 14. The flattened sides are indicated inFig. 14 as 83, 84, and 86, being preferably arranged at such an anglethat the central portion of the throttle is considerably thickened. Arow of holes 81 extend from the surface 83 intocommunlcation with thelongitudinal groove 16 in the throttle shaft. It will be apparent from aconsideration of Figs. 14 to 17 that the holes 81 open above the normalgas level when the throttle is in closed position, and that theiropenings would sink progressively to and below this level as thethrottle is opened. The flow of gas is thus facilitated in accordancewith the added requirements due to wide throttle openings. The openingof the holes 81 is preferably just below the widened portion of thethrottle, which itself '0 drops below the axis of the throttle, as thelatter .is opened. The holes thus lie in the zone of low pressurecreated within the passage 16 due to theincrease in velocity of the airflowing by the constricted zone formed by the presence of the thickenedportion of the throttle. The throttle is held firmly in position on theshaft 43 in any convenient way as by a set screw 88, preferably setopposite the groove 16 so as to prevent leakage between the edges ofthis groove and the throttle. The distribution. of'fuel flow across thepassage l6 may need to be varied to suit particular installations andwith the-construction described above this can be done by varying thesizes, number, and location of the several holes 81, or by varyingthe'sizes, number, and location I of the holes 15 or the form of thegroove 16.

The carburetor is provided with a starting system similar in its generaloutline to that described in my prior application referred to above,although having certain features of advantage.

Referring particularly to Figs. 6 and 13, a screw plug is threaded intoa hole in the upper portion of the float chamber casting 22, having alower conical end adapted to fit against a conical 75 how I00.

seat SI with the intervention if desired of a suitable gasket. The plug90 has a hole 02 extending longitudinally through it, this hole havingan enlargement 93 joined with the main portion of the hole by a conicalseat 94. Within the plug 90 is located a plunger 96 having an enlargedportion 9'! fitting within the enlargement 93 of the plug and providedwith conical surfaces 90 and 99 adapted to fit against the surfaces 94and SI respectively. A longitudinal bore I extends part way up throughthe plunger 06 and has a radial hole IOI extending from it to thesurface of a reduced portion I02. Radial holes I03 also extend from thebore I00 to the surface of the en-- largement 9'7. p

The lower end of the plunger 96 has an enlarged bore adapted to receivethe upper end of a tube I05 extending between the float carrying arms 3|and having a hole I06 (Fig. 3) opening into the float chamber well belowthe fuel level therein. Communication is thus established between thefuel in the float chamber and the At its lower end the tube isconveniently supported by an end piece I01 having a flange I08 restingagainst the lower end of the tube and a plug I09 extending into thetube. A spring I I0 surrounds the member I01, being compressed betweenthe flange I00 and the lower end of a recess III formed in the bottom ofthe float chamber. The plunger 96 is thus normally held in elevatedposition and is guided for a limited vertical movement. The tube I05 islocated in what may be termed the hydraulic center of the fuelreservoirs, so that its action is substantially unaffected by the tiltof the car.

Extending in a generally horizontal direction through the upper portionof the float casting chamber 22, so as to intersect the vertical bore inwhich the plug 90 is threaded, is a bore H2.

This bore is provided with screw threads II3 on its outer end and with aconical seat II4 forming the connection between the main horizontalportion of the bore and a downwardly extending hole II5 entering intothe float chamber. A needle valve I I6 is threaded into the bore so asto oppose the seat I I4 and is held in adjusted position by a frictionspring 1. This needle valve serves to vary the flow of air from thefloat chamber past the starting plunger 96 as will be described below.The bore II2 registers with a bore I20 formed in the main carburet= rcasting I5. This latter bore in turn registers with a vertical bore !2Idrilled downwardly besidethe main conduit I6 and having holes I22 andI23 entering this conduit respectively just above and substantiallybelow a horizontal plane passing through the axis of the throttle. Thehole I23 is below the throttle and at all times clear of it. The upperportion of the bore I2I is closed as by a plug I24. The

holes I22 and I23 are displaced from thecentral vertical plane of thethrottle as will be best seen from Fig. 1, the section line 33 on whichFig. 3 has been taken having been chosen so as to show these holes insection. A diagonal hole through the throttle joining the upper portion.8 thereof with the spherical side 821s adapted to make connection withthe hole I22.

The operation of the improved carburetor will be considered first whenthe parts are in the position for starting the engine. Under theseconditions the plunger 96 will b"! .eEd down as by a bell crank I30operated from the driver's seat in any conventionalmanner or by athermostatic arrangement. The throttle is nearly closed as in Fig. 14.The condition of the starting plunger when depressed is shown in Fig.13' in which it will be seen that communication betwen the upper portionof the float chamber and the passage II2 cut off by contact of thesurfaces 99 and SI and that the only air flow that can take place ispast the needle valve II6. Flow of fuel however can take place throughthe hollow tube I05,

and the .holes IOI and I03.. Fuel thus passing up the tube I05 under theinfluence of the engine suction will be drawn through the trans- "versepassage II2, and mixed with the air passing the needle valve H6. Somefuel may pass through the main throttle openings SI'but the main flowwill be through the hole I 23 which is below the throttle and thussubject to the suction of the engine under the metering control of thejet I06. A rich mixture suitable for starting is thus produced, whichmay be increased temporarily still further by a few quick openings ofthe throttle, causing a priming action by ejection of fuel through themain fuel openings by the action'of the fuel arm. It will be noted thatthe starting system operates by delivering a mixture of the correctrichness without restricting tne air passage as with the usual choke.

When the engine has warmed up the bell crank I30 may rocked to releasethe plunger 96, which then rises under the influence of the spring I I0to the position shown in Fig. 6. In this position the holes I03 are cutoff from the passage II2 but are opened through the enlargement 93 tothe top of float chamber 25. Air will therefore pass into the hollowplunger through the with this effect of holes I03, prevents the changesin the amount of fuel passing through hole IOI that would occur were IOIof large size and subject to a fluctuating hydraulic head. At the sametime the richness of the mixture will be cut down by the fact that thepassage I 0| is.

the only one connecting the fuel tube I05 with the passage II2 whereasformerly both the/hole IOI and the holes I03 acted in this manner. Withthe throttle practically closed a mixture of fuel and air suitable foridling, when augmented by the flow of air past the throttle, andcontrolled by the adjustment of the needle valve H6 is supplied to thepassage I6 through the hole I23.

As the throttle is opened for normal running of the engine at ordinaryspeeds the air flow past the end 8| of the throttle will produce a lowpressure zone into which the fuel discharging-from the holes 81 willpass. The holes themselves open lnto a portion of this zone of ratherhigher pressure than its minimum and some dilution of the mixture isaccomplished by passage of air past the end 62 of the throttle. As thethrottle is opened more and more to give in creased speed to the motorthe holes 81 not only drop below the fuel level and thus increase thegravity flow of fuel through them but at the same time enter more nearlyinto the low pressure zone caused by the constriction in the passage I6.This is clearly illustrated in 'Figs. 16

and 17. It will be observed that in Fig. 17, which side of the throttle,i. e. the side remote from the holes 81, passes less and less air owingto the constriction of that side of the passage by the widened portionof the throttle, This furnishes a way of reducing the dilution of themixture and thereby increasing its richness as is required for fullpower.

Under normal running conditions, as the engine changes from slow idlingspeed to the speeds generally adapted for open country travel, it isdesirable to shift more and more of the fuel supply from the startingsystem to the main throttle and to do this gradually and without anyabrupt changes. This result is of course partially accomplished by themere opening of the throttle .which satisfies some of the motor suctionso that the suction on the passage H2 is reduced. The hole I however,isso positioned that as the throttle is in substantially closed positionit registers with the hole I22 and'permits passage of air from thenppersurface of the throttle to this latter hole. A partial satisfaction ofthe suction exerted through the hole I22 is thus brought about and thesupply of fuel through the starting system reduced. As the throttle isopened the hole I25 gradually moves out of registry, closing the holeI22 and thus reducing the neutralizing effect of the passage I25 on thegas flow through the passage I23. This compensates for the decrease insuction resulting from the partial opening of the throttle. The hole M3is so proportioned as to supply more fuel than is required for idling,but the right amount for speeds just above idling. The neutralizingaction of passage I25 corrects the flow at idling speeds to the correctamount by drilling the hole I25 at an angle as shown, its opening ontothe throttle surface is in the form of an ellipse, making much moregradual the change of registration of the hole I25 with respect to thehole 822 as the throttle opens.

Fuel passing through the holes 81 in the throttle must of necessity comethrough the passage 55 in the fuel arm. The fuel can reach that passagedirectly through the jet I30; through the hole H and the groove I0,which as described above are eifective only at high throttle openings,and through the nozzle I3I and the holes 60 if that nozzle is used. Forordinary operation the entry through nozzle I30 alone needs to beconsidered. The fuel in the chamber 55 is subject to several forces,considering the arm 42 to be stationary. The-first is -..the hydrostatichead of fuel in the float chamber, causing the fuel to seek'the floatchamber level in the throttle bore 54. The second is the pressureexisting in the mixing chamber H5 at the outlet holes 81. The third isthe pressure existing above the fuel level in thefloat chamber asdetermined by the with-' drawal of air through passage H2 and its entrythrough the jet I3 and the chain of passages 49, I40, 48, and 5i. Thefourth is the air pres-- sure in the arm chamber 56 as determined by itsconnections with the float chamber through 59, 48, and 5t, and with themixing passage through 59, I40, 41 and 49. It will be apparent that anydesired balance between these pressures can be secured by a properproportioning of the various jets, and that the desired balance forspecific inspeeds, substantially no pressure drop occurs in.

undesirable.

the float chamber. II. the jet I! were so restricted that the air takenout through passage I I2 caused a substantial pressure drop in the floatchamber a reverse air flow from the throttle would take place, drainingthe bore 54 and a part of the chamber 55. This would prevent instantflow of fuel on opening the throttle and'would be The reason for thiseffect is ap parent when it is considered that during idling and lowmotor speeds with the throttle nearly closed the holes 81 are subjectedto nearly atmospheric pressure.

The size of the jet 13 can also be chosen to give a leaning effect asthe motor speed increases with constant throttle opening (as when a downgrade is encountered) and therefore to improve the economy of operation.The reduction in pressure at the hole I23 and at the throttle openings81 increases with the air speed past the throttle, on

, account of the greater conversion of pressure head into velocity head.If the float chamber pressure is kept substantially atmospheric byadmitting enough air through jet I3 the gas flow through the holes 81and I23 would be increased as the differential pressure went up. Byreducing the size of jet 13 the float chamber pressure may be lowered toany desired degree as the pressure at 8'! and I23 is lowered, since theincreased air flow out of these holes will cause a drain of air from thefloat chamber which will lower the pressure therein to a balancedetermined by the freedom of entry of air through the jet I3.

The angle at which the jet 13 opens into the mixing passage I6, as wellas its vertical position in the passage, can also be used to regulatethe action of the carburetor under different conditions. If, forexample, the jet points straight up the static air pressure upon it willbe augmented by the velocity head of the air when the motor operatingcondition is such as to produce a large air flow through the passage I6.If .the hole is tilted at a substantial angle the aspirating effect ofthe air rushing past it at high speeds will.

cause the static air pressure to be reduced by the amount of thisaspirating action. Between the extremes possible lies a range which maybe utilized to cause the carburetor to adapt itself automatically to therequirements of the particular engine to which it is applied. As oneexample, there is a reduction in the air pressure within the mixingpassage as the air velocity through it increases (considering thethrottle opening constant) due both to the increased conversion ofstatic pressure into velocity head and to the effect of frictionalresistance. This would result in the diiferential pressure between thefloat chamber and the fuel openings being increased, richening themixture. By a suitable change in the angle of the nozzle 13 theaspirating effect may be made use of to reduce the float chamberpressure with increasing air flow in the same or a slightly greaterratio as the reduction of pressure in the mixing passage, keeping therichness of the mixture constant or leaning it somewhat. The leaningeffect of the nozzle I3 is more pronounced at higher air speeds throughthe mixing passage.

The nozzle 15 can if desired be extended to a point such that thetemperature of the air entering it is determined by the warmth oftheengine. By this means the float chamber pressure will be reducedautomatically as the engine warms up, producing thermostatic control ofthe richness oi. the mixture without. the use of any moving parts. Whenthe throttle is suddenly opened the fuel arm 42 isswung in acounterclockwise direction as viewed in Fig. 5. This forces the fuel inthe right hand portion of the fuel chamber to flow much more rapidlyinto the jets I38 and I3I' and therefore out of-the throttle openingsand also forces a sudden stream of fuel out through the passage 7 andthe jet 50. Both of these effects act to greatly richen the mixture atthe instant of acceleration. It will be observed that the main portionof excess fuel fiows through the main fuel opening of the throttle, thisbeing a very desirable condition as better atomization of the fuel canbe secured thereby. If the throttle is rapidly closed a reverse actionoccurs, the fuel arm 52 moving clockwise as viewed in Fig. 5. The

passage 6'! being in communication with the atmosphere, air is drawninto the fuel chamber temporarily and the flow of fuel through thethrottle openings is very substantially reduced. This is an. extremelydesirable condition as it avoids the flooding generally accompanying asudden reduction of speed in the motor.

In Fig. 18 a modified idling system is shown, in which the adjustmentfor starting has been eliminated and much greater simplicityhas beenattained. In this figure the parts generally similar to those in theform previously described have been designated by primed numerals. Intothe bottom of the cap casting 22' enclosing the float chamber 25' is seta tube I50 having a hole I! near its bottom. A screw I52 is threadedinto the upper part of the casting, and bears a second tube I53extending through a hole I55, generally corresponding to the hole H5 ofthe previously described form, and into the tube I50. The sizes of thetwo tubes are sufficiently dissimilar so that a free space for fuelexists between them, the outer one acting as a fuel well having a singleinlet IEI. A conical enlargement I55 of the tube I53 extends into thehole IBA so that an adjustment of the amount of air passing from thefloat chamber into the passage H2 can be regulated by turning the screwI52. A hole I56 opens from the interior of the tube L53 into the upperportion of the float chamber, above the fuel level; and a hole I51 opensfrom it into the passage H2. These holes act like the holes I03 and NIin the form first described.

With this modified construction the screw I52 is set so that the properidling adjustment is obtained when the motor is warm, the additionalenriching of the mixture required for starting the cold 'motor beingobtained by opening the throttle rapidly one or more times. This acts,as in the case of acceleration previously described, -to

' cause the fuel arm to eject fuel through the openings 49 and 81. Oneadditional feature of this modification will also be considered. It willbe apparent that whereas the passage of fuel through the tube I53 isgoverned by the differential of the various air and liquid pressuresacting, the entry of fuel into the outer tube I50 through hole I5I isgoverned solely by the static head of the fuel in the float chambersince the top of the tube' I50 is open to the interior of the floatchamber. In idling the hole I5I keeps the level within tube I50substantially up to the level in th float chamber. The idling systemsupplies practically all of the fuel at idling speeds, and continues tosupply a major portion of the fuel at low driving speeds. Inoneinstallation which has proved successful the amount of fuel supplied bythe idling and throttle openings is about even inthe neighborhood of 25miles per hour. Above this speed, or at heavier loads, the throttleopenings predominate in the supply of fuel. As the "differentialpressures feeding fuel through the jet I23 increase beyond the capacityof hole IBI the level within tube I50 drops, and the fuel the car speedwithout increase in throttle opening, due to a lightening of the load,would tend to reduce the pressure at the opening 523, which is in thelowest pressure zone of the mixing passage. Were this not counteractedthe differential pressure feeding fuel through I23 would be increased,giving an undesirably rich mixture.

It is desirable to lean down the mixture under these conditions topromote economy. With the idling system just described there is adefinite maximum limit to the amount of fuel which can be fed through itin a given time. Any influences, such as a speeding up of the motor duei to decrease of load, which decrease the pressure at the opening I23without requiring an opening of the throttle, thus act to decrease thepercentage of the fuel requirements supplied by the idling system. Theeffect of the tube I 50 is thus somewhat similar under light runningconditions to that exerted by the angle of the jet It at higher speeds.

In the form shown in Fig. 19 a tube I 60 surrounds the tube lIlE of Fig.6, and has a hole IGI near its bottom. Except for this change the idlingsystem is exactly as shown in Figs. 6 and 13. The effect of the outertube, which is open to the float chamber at its top, is the same as thetube I59 of Fig. 18. The idling system of Fig. 19 is substantially thesame as that shown in my prior application Serial No. 682,980 exceptadvantages in simplicity of manufacture.

' In Figs. 20 and 21 a. modified form of throttle is shown, in which agroove I65'is used in place of the hole I25. -This grove registers withthe hole I22 in the mixing passage wall, and has a varying contour or anintermediate partition I66 set so that when the throttle is closed theparti tion is just below the hole I22. This hole is preferably set sothat it lies on a horizontal plane through the axis of the throttle, andwith the partition I66 located below it, is in communication with theupper side of the throttle. The same effect is thus produced as withhole I25 in subjecting the hole I22 to substantially atmosphericpressure and reducing the fuel flow through hole I23. As the throttle isopened the I25 and the connection to the engine side was formed bythemovement of the rear side of the throttle above the hole I22. Thepartition is preferably set at an angle in the groove to still furthersmooth the transition. The location of the hole I22 circumferentiallyofthe throttle may be chosen so that the portion of the throttle whichblocks the hole moves over the hole with any desired relative speed. Itwill be apparent that the further the blocking portion of the throttleis removed circumferentially from the axis of the throttle the greaterwill be its speed with relation to a given angular speed of thethrottle, and the more abrupt will be the transi tion between the twoconditions referred to above.

In Figs. 22 and 23 is shown a modification of the fuel arm so that awell or reservoir is provided in it by which a continued enrichment ofthe mixture is obtained during acceleration. In principle the action ismuch the same as the well I20 shown in my prior application. In thepresent case the groove 41' (corresponding to the groove 41 of the formfirst described) is widened and deepened to form a well I'll) connectedby a passage III with the chamber 56 in the fuel arm. As the fuel arm isswung counterclockwise in Fig. 5 to open the throttle fuel will run upthe groove 41 and fill the chamber "0. This fuel will run out graduallythrough the hole I'll, and will continue to enrich the mixture (both byadding to the amount of fuel ,in chamber 56 and by decreasing the airfiow to that chamber due to its passage through the metering jet 59 andthe chamber itself) for a sufiicient time to complete acceleration ofthe motor; thus carrying on the effect of the fuel ejected through theopenings 81 and 49 by the quick opening of the throttle. If the throttleis closed before the well I'll] is drained the remaining fuel will bedrawn back into the fuel chamber through the groove 41'.

In Fig. 24 is shown an air metering jet I15 substituted for the screwI24. Such a jet is useful in regulating the engine speed at which thesupply of fuel is taken over from the idling system by the throttleopenings 81. By admitting air to the idling system at I15 the depressingeffect of the operation of this system on the float chamber pressurewill .be neutralized to a degree depending on the size of hole in thejet I I5. This raising of float chamber pressure will cause increasedflow of. fuel through the throttle openings 81 at low throttle openings,but will have relatively little effect at wider throttle openings as itis then exceeded in its effect by the other forces acting. Theeconomizing effect of the idling system at intermediate engine speeds,referred to above, can also be controlled by this means.

The cross sectional shape of the throttle can be varied to produce whatvariations in the quality of the mixture may be required at differentthrottle openings and engine speeds. For example, a change in throttleshape so as to cut down the gap between the left hand side of thethrottle and the adjacent wall of the passage I 6 in Fig. 17 will causea greater air velocity at this point with a consequent decrease inpressure. This increases the diiferential pressure acting on the fueldischarging through the throttle openings.

- A change in the contour of the other side of the at ill with some airflowing through. Indeed,

by a shift in the holes 81 towards the adjacent throttle edge it ispossible to do away with the idling fuel supply entirely, as the reducedpressure into which the holes 81 open will cause fuel flow through themat idling speeds. The additional fuel required for starting can beobtained by successive openings of the throttle to cause the fuel arm toforce fuel out of the holes 81. In case this system is adopted the tubeI05 and plug of Fig. 6 are omitted and the holes through which theypassed closed. The air passages IIS, II2, I20, I22, I23, and the needleIIG, are kept, however, in order to exert the governing effect on thefloat'chamber air pressure described above.

I claim:

1. A carburetor having a mixing passage, 9. throttle rotatable on atransverse axis therein, a main fuel supply opening into the passage, anauxiliary idling jet opening into the mixing passage on that side of thethrottle which is towards.

the engine, a fuel passage supplying fuel to said jet, an opening fromsaid fuel passage to a point in the mixing passage on the atmosphericside of the throttle, said opening being positioned so as to be coveredby the throttle when the throttle is closed, and an air duct in thethrottle positioned to register with said opening when the throttle isclosed to admit air under substantially atmospheric pressure to saidopening and thereby reduce the flow of fuel through the auxiliary idlingjet, and to pass by said opening as the throttle opens.

2. A carburetor having a mixing passage, a throttle rotatable on atransverse axis therein and having a plurality of fuel passages spacedapart along the surface of the throttle in the general direction of theaxis of the throttle, a hollow shaft supporting said throttle, means forsupplying fuel to said hollow shaft, a distributing passage formed inthe mating surfaces of the shaft and throttle and extendinglongitudinally of the shaft a suflicient distance to open into all ofsaid fuel passages and permit distribution of fuel through them, and aplurality of spaced openings between said distributing passage and thehollow interior of the shaft.

3. A carburetor having a mixing passage, a throttle rotatable on atransverse axis therein and having fuel passages opening onto itssurface, means for supplying fuel to said passages, an idling jetopening into the mixing passage on that side of the throttle towards theengine, a fuel passage supplying fuel to said jet, and an air ductregistering with a by-pass in the throttle valve in certain positions ofsaid throttle valve for admitting air to said fuel passage atsubstantially the pressure of the air in the mixing passage at a pointadjacent the throttle valve, thereby to reduce the flow of fuel throughthe jet in certain positions of the throttle.

4. A carburetor having a substantially cylindrical mixing passage, athrottle pivoted within the passage on an axis transverse thereto, saidthrottle being formed as a sphere having the diameter of the inside ofthe mixing pmage, and, flattened along four faces to produce a thickenedportionat one side of the axis, and having fuel passages opening ontoone of said flattened faces adjacent the thickened portion, and meansfor rotating the throttle from a closed position extending across themanifold to an open position in which the thickened portion lies on thatside of the throttle axis which is towards the engine.

5. A carburetor having a substantially cylindrical mixing passage, athrottle pivotedv within the passage on an axis transverse thereto, saidthrottle being formed with a thickened portion at one side of thethrottle axis and with fuel passages opening into the throttle surfaceadjacent said thickened portion, and means for rotating the throttlefrom a closed position into a position in which the thickened portion ofthe throttle lies on that side of the axis which is towards the engine,the throttle being so shaped that when it is in fully open position theenlarged portion is spaced further from the passage wall on that side ofthe throttle containing the fuel holes than on the opposite side.

6. A carburetor having a mixing passage, a throttle rotatable on atransverse axis therein and having fuel passages opening onto itssurface so positioned as to pass towards the engine side of the axis asthe throttle is opened, means for supplying fuel to said passages, anauxiliary idling jet opening into the mixing passage on the engine sideof the throttle, a fuel passage supplying fuel to said jet, an openingfrom said fuel passage into the mixing passage so as to be closed by thethrottle when the throttle is closed, and an air duct in the throttleadapted to register with said opening when the throttle is closed toadmit air to said opening and thereby reduce the flow of fuel throughthe auxiliary idling jet.

v in cross-section on a plane transverse to said axis of rotation, saidthrottle ha ing fuel passages opening onto a surface thereof which islocated above the axis of the throttle when the throttle is closed, andpositioned to descend within the mixing passage when the throttlerotates towards open position, said fuel passage openings being locatedadjacent the thickened portion of the throttle, and means for supplyingfuel to said passages at a level below that of the openings of the fuelpassages when the throttle is closed but above said openings when thethrottle is open.

8. A carburetor having a substantially cylindrical vertically extendingmixing passage, a throttle mounted for rotation upon a transverse axistherein, said throttle being substantially circular in cross sectionwhen viewed on at least one plane including the axis of rotation wherebyit may substantially close the mixing passage when in one position ofrotation, and being asymmetrically thickened in its middle and taperedtowards its ends when viewed in cross section on a plane transverse tosaid rotation, the thicker portion being towards the engine manifoldwhen the throttle is closed, said throttle having fuel passages openingonto its surface adjacent its thickened portion and on the side of thethro tle remote from the engine manifold when the throttle is closed,whereby when the throttle is opened the fuel passage openings will beloweredwithin the passage and a greater space will be left between thethrottle and the mixing passage on the side of the throttle where thefuel passages are located, and means for supplying fuel to saidpassages.

9. A carburetor comprising a mixing passage, a throttle therein, aconstant level supply chamber, a main fuel jet opening onto the surfaceof the throttle, means conducting fuel and air from said chamber to themain fuel jet, an idling jet opening into the mixing passage on. theengine side of the throttle and connected both below the fuel level insaid chamber to withdraw fuel therefrom and above the fuel level thereinto draw air therefrom, and a metering jet opening into the mixingpassage on the side of the throttle remote from the engine and connectedto said chamber above the fuel level therein to control the differentialpressure between the chamber and the first-named jets.

.10. A carburetor comprising a mixingpassage, a throttle therein, aconstant level supply chamber, a main fuel jet opening onto the surfaceof the throttle, means conducting fuel and air from said chamber to themain fuel jet, an idling jet opening into the mixing passage on theengine side of the throttle and connected both below the fuel level insaid chamber to withdraw fuel therefrom and above the fuel level thereinto draw air therefrom, and a jet opening into the mixing passage on theside of the throttle remote from the engine and connected to saidchamber above the fuel level therein.

11. An idling system for carburetors comprising a mixing passage, afloat chamber, a well open at its top to said chamber above the fuellevel thereinand having a restricted opening into said chamber below thefuel level therein, an idling jet opening into the mixing passage, andconnections from said jet to the chamber above the fuel level thereinand to said well beneath the normal fuel level therein, whereby theadmission of fuel into the idling system cannot exceed, for more thanthe time required to drain the 'well, the amount entering the wellsolely under the static pressure of the fuel in the float chamber.

12. A carburetor having a mixing passage, a throttle therein, a fuelchamber, a float chamber, a fuel arm connected to the throttle,cooperating with the fuel chamber to form a pump, and oscillating in thefuel chamber, a mainfuel passage through the arm and opening into thesurface of the throttle, a well formed in the, upper part of the arm, aconnection between the fuel chamber and the float chamber including acheck v .lve to prevent back flow, a passage leading from said well tothe fuel chamber up which fuel may be forced on a throttle-openingmovement of the arm and down which it may run on a throttleclosingmovement thereof, and a passage from said well to the main fuel passage.

13. A carburetor having a mixing passage, a fuel jet therein, a throttlein the mixing passage,

a fuel chamber, means for maintaining a substantially constant level offuel therein, a swinging arm in said chamber connected directly to thethrottle for movement therewith, a float chamber, a connection betweenthe float and fuel chambers to supply the fuel chamber with fuel at asubstantially constant level, a check valve in said connectionpreventing reverse flow of fuel to the float chamber when the swingingarm is moved by the opening of the throttle, a pair of passages in saidarm each having openings leading into the fuel chamber on that side ofthe arm which is forwardly positioned as the arm is moved by the openingof the throttle, one of said passages having an air supplying connectionand openings leading into the second passage, said air supplyingconnection being so positioned as to be blocked by an excess of fuelwhen the arm is moved by a rapid opening of the throttle,

JOHN ROBERT FISH.

till

